Magnetic device



' Sept 2,1930. H R. VAN DEVENTER MAGNETIC DEVICE Filed April 22, 1924 INVENTOR $5 9 J Harry R lmfiwewer ATTO NEY as tion will appear tion and the peculiar features thereof are de- 40 thin sheet of some insulating substance ,which d will be effectually isolated from one another; j

I 60 oneanother to beallincon Patented sept. 2,1930

UNITED S ATES PATENT OFFICE,

HARRY a. van nEvEN'rEia, or NEW YORK, N. 1., ASSIGNOR ro-nummnn. CONDENSER conro'aa'rioiv, or NEW YORK, N. Y.,, A coaron'a'rioiv or nnnawm MAGNETIC DEVICE Application filed April 22, 1924. Serial No. 708,318.

This invention relates to improvements in magnetic devices; especially devices to aflor electrical and magnetic conductance in signalling and other electrical arts.

An object of the invention is to provide a magnetic device of novel construction with constituent arts which have relatively great thinness and vice being capable of affording suflicient magnetic conductivity and keeping the losses at a minimum in actual operation.

Another object of my invention is toprovide a laminated magnetic core which substantially reduces eddy current and hysteresis losses, and is, therefore, particularly adapted for use in devices employed in high frequency circuits.

I desire my invention to be understood as including a magnetic device having the characteristics .above mentioned; the parts or elements thereof, and the method by which such -.a device and the parts composing it are produced. a v

Other objects and advantages ofmy inven from the following descripfined in the appended claims; but I of course reserve the rig t to vary the details of structure or proceeding herein specificall se so forth, to the full extent compatible wit the broad meanings of the terms in which the claims are expressed.

In the drawing Fig. 1 shows .a magnetic core constructed in accordance with my invention; Fig. 3 is an exploded view of Fig. 1; and

Figs. 2 and4 show other forms of magnetic cores.

In the practice of my invention, I take a may be fibrous material, such as paper an 5 read thereon a cient-quantity of finely Til vl'ided particles to form a continuous layer.

ductive, andare distributed evenly over the surface of the sheet and caused to adhere thereto. At t e same time the iron particles. must be attached to the paper close enough to can easily be produced; the de-.

articles must be iron orsomething else 46 that is both electrically and magnetically conthus giving one side 0 continuity to the layer and eliminating open spaces or air gaps. To spread the metallic particles over the surface of the paper, any feasible methodcan be chosen. For example, I may make use of the well known Schoop process, by which iron dust is blown or sprayed against the paper, being forcibly impelled against the surface thereof and caused to fill the microscopic recesses or depressions in same, and to stick to the fibers of the paper, and thus aiford a thin or tenuous layer covering the paper over its entire extent. The proccss maybe performed inan atmosphere of nitrogen, carbon dioxide, or some other me dium that will not support combustion, to prevent oxidation of either the metallic particles or the paper. The paper may sheets, and may thus becovered with a continuous thin layer of particles on one side or both. After, covering, the laminated element so produced can be coated with thin varnish or any other suitable non-conducting substance to protect its surface, keep the layer from being rubbed off, and to add some stiffness to the element when dried after coating. The strip or sheet with the layer thereon can be trimmed when finished and cut into lamit nated elements of the requiredlength and width. v

To make amagnetic core for transformers or coils out of such elements, for instance, a number of elements are superposed one upon another and bound together. The elements ma consist -of a sheet of paper with a magnetic layer. on one side with or without a nonconductive coating ;because if the elements are assembled with the untreated surface of the aper of one against the metallic layer of another, the magnetic layers of the entire core be in the form of strips or but when given magnetic layers on both sides of 'the paper, each conductive coating all over it.

Figs. 1 and 2 show well known formsof a magnetic core for windin 3 in which the elements 1 and 2 are made in accordance with my invention and are built to form' a laminated core. The element 1 may be coatedon nly and thus tseoatmg separated element must have a non- 2 1,774,856 from 2, or if varnish is used to cover the dug the thin strip or sheet .with the conductive netic material both sides may be coated, the layer may be varnished or not, as desired. varnish serving to laminate the core. The By this invention conduct ve elements in laminated eflfect is shown by the exploded the form of laminations or strips to be rolled, 5 view of Fig. 3. can be produced having a thinness of a qu'ar- 70 With my invention laminated elements of tar or ahalf of amil, or one-thousandth of an relatively small thinness can be made, and inch. yet have the necessary permeability while Having described my invention, what I keeping the eddy current and other losses to lieve to be new and desire to secure and the smallest possible amount. 7 7 protect by Letters Patent of the United States 75 Due to the very high frequency currents iszem loyed in radio circuits, very considerable 1. A magnetic core made up of laminated add} Current and hysteresis lo ses are inelements superposed one uponanother, each curred Whenthe usual type of core is used, element comprising a thin layer of'magnetic and my construction is therefore particularly material consisting of finely divided particles adapted for use in radio apparatus. in contact with one another, giving continuity In Of blowing spr ying the m gto the layer, andinsulation between the laynetic dust or particles against the paper, I ers,'said particles being held by adhesion to may obtain such particles by precipitation one th d t aid insulation.

20 from It iq id Containing a Solution of some 2. A core for electro-magnetic apparatus compound in which th iron like comprising a plurality of elements in the Occurs; and than spreadlng the precipitate form of thin plates which are insulated from Out thinly ver th in l ing Sheet'in a y one'another, each element including a nonmanner capable of yielding the desired remag ti a ri h t u n hich there is 5 sults; or the magnetic particles can be pr -deposited finely divided magnetic material.

' cipitated directly upon the sheet, deposited 3, A core elem nt for eleetro-magnetic apin a continuous layer distributed all over the e -em on isting of a sheet of non-metallic Surfacmaterial havinga coating of finely divided Instead of i g laminations for m gparticles of ferro-magnetio material. a0 netic cores,-I may also employ long and rela- 4. A core element for a magnetic circuit tively narrow strips 4 of thin insulating-main a high frequency apparatus consisting of terial covered in the manner above set forth l mi a of non-magnetic material, one or with a layer of iron-particles, and then wind more f th surfaces of id lamina being the r p into 1 p spi l, Shown coated with ahighly divided deposit of magpl y either as a gn core or as a 5. 'A core for electro-magnetic apparatus coil for the passage of electric current, such comprising h t;v f insulatin material as a loading inductance coil in radio, or'in' having a. coating of finely divide particles signalling with wires. of ferromagnetic material.

40 811 p p is used to receive the layer of 6. A core for electro-magnetic apparatus. 1 particles, a binder may be utillzed t make comprising a. sheet of flexible insulating mathe particles adhere to the paper. For this t i l having acOatin'gof finely divided parpurpose, the paper may be covered or lightly ti le of farm-magnetic material. impregnated with a thin soft wax, and when imony' whereof I afiix my signature.

5 the particles come into contact with the wax HARRY- R. VAN DEVENTER.

" they stick to it. After the layer'is fully formed, the paper and the layer can be rolled, compressed, or squeezed, both to expel the surplus wax and to make the final product 50 t inner.

Instead of paper, thin sheets or strips of any other suitable material may be utilized to receive the layer of particles. For example, I may take some ofthe compounds of 65 ce lulose, such as are employed in making I films for photography, and treat the surface thereof with a liquid capable of dissolving the film, but only to the ,extent of making the surface sticky, so that the magnetic par- 60 ticles will adhere; or I may take the thin gelatinous substance which is attached to a r photographic film to give it the light-sensitive coating, and cover this film with the magnetic layer under conditions which will 6 permit adhesion to take place. In any case 

